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Analog modulation
  • AM
  • FM
  • PM
  • QAM
  • SM
  • SSB
Circuit mode

(constant bandwidth)

  • TDM
  • FDM / WDM
  • SDMA
  • Polarization
  • Spatial
  • OAM
Statistical multiplexing

(variable bandwidth)

  • Packet switching
  • Dynamic TDMA
  • FHSS
  • DSSS
  • SC-FDM
  • MC-SS
Related topics
  • Channel access methods
  • Media access control
  • v
  • t
  • e

Code-division multiple access (CDMA) is a channel access method used by various radio communication technologies.

CDMA is an example of multiple access, where several transmitters can send information simultaneously over a single communication channel. This allows several users to share a band of frequencies (see bandwidth). To permit this without undue interference between the users, CDMA employs spread spectrum technology and a special coding scheme (where each transmitter is assigned a code).

CDMA is used as the access method in many mobile phone standards. IS-95, also called "cdmaOne", and its 3G evolution CDMA2000, are often simply referred to as "CDMA", but UMTS, the 3G standard used by GSM carriers, also uses "wideband CDMA", or W-CDMA, as well as TD-CDMA and TD-SCDMA, as its radio technologies.